Method for producing grain oriented silicon steel comprising copper

ABSTRACT

Silicon steel alloy melt composition and method for forming grain oriented silicon steel sheets therefrom, characterized in that the resulting sheets have a cube-on-edge texture with permeabilities at 10 oersteds as high as or higher than 1850. The alloy from which the steel is formed preferably contains silicon, sulfur, aluminum, manganese, nitrogen and copper. Maximum permeability is obtained when the steel being processed has a ratio (by weight) of manganese equivalent to sulfur of greater than 2.0 and less than 4.75. It is essential to provide both nitride and sulfide formers which act as primary grain growth inhibitors in a duplex primary grain growth inhibition system to effect the desirable results of the invention.



1. IN A PROCESS FOR PRODUCING ORIENTED SILICON STEEL INCLUDING THE STEP OF PREPARING A MELT OF STEEL AND CASTING SAME INTO INGOTS, HOT ROLLING SAID INGOTS TO HOT ROLLED BAND GUAGE AN D SUBSEQENTLY COLD ROLLING AND ANNEALING, AS DESIRED TO PRODUCE SILICON STEEL WITH CUBE-ON-EDGE ORIENTATION, THE IMPROVEMENT WHICH COMPRISES PREPARING A MELT OF STEEL HAVING A COMPOSITION CONSISTING ESSENTIALLY OF: CARBON .02 - .07% MANGANESE EQUIVALENT .05 - .24% (%MN + (0.1 TO 0.25) + %CU) SULFUR .01 - .50% SILICON 2.5 - 3.5% ALUMINUM 0.15 - .04% NITROGEN +-90 PARTS PER MILLION COPPER 0.1 TO 0.3% IRON BALANCE AND WHEREIN THE RATIO OF MANGANESE EQUIVALENT TO SULFUR, BY WEIGHT, IS IN THE RANGE OF 2.0 TO 4.75, AND THEREAFTER PROCESSING SAID STEEL TO PRODUCE GRAIN ORIENTED STEEL WITH CUBE-ON-EDGE TEXTURE WHEREBY SAID ORIENTED STEEL HAS A PERMEABILITY OF AT LEAST 1850 AT 10 OERSTEDS DUE TO A DUPLEX SULFIDE AND NITRIDE PRIMARY GRAIN GROWTH INHIBITION SYSTEM, SAID SYSTEM RESULTING FROM THE AFOREMENTIONED CHEMISTRY OF THE STEEL PROCESSED; SAID PROCESSING INCLUDING THE STEP OF SUBJECTING SAID HOT ROLLED BAND TO A TEMPERATURE ABOVE 1400*F FOR 10 SECONDS TO 30 MINUTES, SAID HOT ROLLED BAND HEAT TREATMENT CONTRIBUTING TO THE ATTAINMENT OF SAID HIGH PERMEABILITY FOR SAID ORIENTED SILICON STEEEL
 2. An improvement according to claim 1, wherein the ratio of manganese equivalent to sulfur is 2.5 to
 4. 3. An improvement according to claim 1 wherein said hot rolled band is heated to 1400*F to 2100*F.
 4. An improvement according to claim 1 wherein said hot rolled band is heated to 1650*F to 1850*F.
 5. An improvement according to claim 4 wherein said hot rolled band is heated to 1650*F to 1850*F for 10 seconds to 5 minutes. 